Anvil assembly with sliding sleeve

ABSTRACT

An anvil assembly is provided. The anvil assembly includes an anvil center rod, a head assembly pivotally secured to the anvil center rod assembly from an operative position to a tilted position, and a sleeve slidably disposed about the anvil center rod. The sleeve is associated with the head assembly such that movement of the head assembly from the operative position towards the tilted position effects proximal movement of the sleeve about the anvil center rod.

BACKGROUND

Technical Field

The present disclosure relates generally to an anvil assembly which issuitable for use with a circular anastomosis stapler. More specifically,the present disclosure relates to an anvil assembly having a tiltablehead with a sliding sleeve.

Background of Related Art

Circular anastomosis staplers which include an anvil assembly having atiltable anvil head are known in the art. One such circular anastomosisstapler is disclosed in commonly owned U.S. Patent ApplicationPublication No. 2008/0230581 (“'581 Publication”) which is incorporatedherein by reference in its entirety. The anvil assembly includes ananvil head pivotally secured on a distal end of a connection post of theanvil assembly. The anvil assembly is provided to a clinician in anoperable position, i.e., with the anvil head perpendicular to theconnection post.

During an anastomosis procedure, a purse string suture may be used toattach first and/or second sections of the tissue being joined togetherabout the connection post of the anvil assembly. Following the firingoperation of the circular anastomosis stapler and as the anvil head isseparated from the cartridge assembly of the circular stapler, the anvilhead pivots about the distal end of the connection post, to reduce theprofile of the anvil head. The anvil assembly may be spring loaded toautomatically tilt the anvil head to a maximum angle allowed by thecircular stapler and/or anvil head geometry. Tilting the anvil head toreduce the profile of the anvil head within a vessel minimizes contactbetween the anvil head and the inner walls of the vessel to facilitateremoval of the anvil head through an anastomosis ring, i.e., the annularstapled section of tissue, formed by the stapler.

In certain instances, an anastomosis donut, i.e., the tissue severed byan annular knife of the stapling assembly during an anastomosisprocedure and the purse string suture(s), if used to secure the tissuesection(s) about the anvil assembly, and/or other tissue or obstructionmay become pinched by the anvil head as the anvil head is pivoted. Whenthis occurs, the anvil head is inhibited from fully tilting. As aresult, the anvil head may contact the interior of the vessel to agreater extent than necessary during withdrawal of the anvil headthrough the anastomosis ring. Contact of the interior of the vessel maycause unwanted tissue damage (i.e., damage to the anastomosis ring)and/or may result in higher refraction forces being necessary duringremoval of the anvil head through the vessel.

Therefore, it would be beneficial to have an anvil assembly including asleeve configured to reposition the anastomosis donut to preventpinching of the anastomosis donut by the tiltable anvil head, and, thus,allow complete tilting of the anvil head.

SUMMARY

Accordingly, an improved anvil assembly is provided. The anvil assemblyincludes an anvil center rod, a head assembly pivotally secured to theanvil center rod assembly from an operative position to a tiltedposition, and a sleeve slidably disposed about the anvil center rod. Thesleeve is associated with the head assembly such that movement of thehead assembly from the operative position towards the tilted positioneffects proximal movement of the sleeve about the anvil center rod.

In some embodiments, the sleeve assembly includes a sleeve body disposedabout the anvil center rod assembly and a distally extending flangepivotally connected to the head assembly. A living hinge may be formedbetween the flange and the sleeve body. The head assembly may include apivotal cam latch member and the flange is pivotally connected to thecam latch member.

In embodiments, the head assembly may include a housing, a post, abackup plate, and a cam latch member. The backup plate may be positionedto prevent pivotal movement of the head assembly from the non-tiltedposition to the tilted position prior to firing of a surgical staplingdevice. The backup plate may be movable to a second position to permitpivotal movement of the head assembly in relation to the anvil centerrod assembly from the non-tilted position to the tilted position. Theanvil head assembly may include a post which is pivotally secured to theanvil center rod, the sleeve member is operably engaged to the post. Thesleeve member may be operably positioned to be engaged by the anvilassembly as the anvil assembly is pivoted from the operative position tothe tilted position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed tilt anvil assembly aredisclosed herein with reference to the drawings wherein:

FIG. 1 is a side perspective view of a surgical stapling deviceincluding an anvil assembly according to an embodiment of the presentdisclosure;

FIG. 2 is a side perspective view of the anvil assembly shown in FIG. 1,with the head assembly in a second or tilted position subsequent tofiring of the surgical stapling device;

FIG. 3 is an exploded perspective view of the anvil assembly shown inFIG. 2;

FIG. 4 is an enlarged perspective view of a cam latch member of theanvil assembly shown in FIGS. 2 and 3;

FIG. 5 is an enlarged perspective view of a retainer member of the anvilassembly shown in FIGS. 2 and 3;

FIG. 6 is a side view of the sleeve member of the anvil assembly shownin FIG. 2-5;

FIG. 6A is a cross-sectional bottom view taken along line 6A-6A shown inFIG. 6;

FIG. 6B is a cross-sectional top view taken along line 6B-6B shown inFIG. 6;

FIG. 6C is a cross-sectional end view taken along line 6C-6C shown inFIG. 6;

FIG. 6D is a cross-sectional end view taken along line 6D-6D shown inFIG. 6;

FIG. 7 is an enlarged side view of a portion of the anvil assembly shownin FIG. 2-5;

FIG. 8 is an enlarged side view of the portion of the anvil assemblyshown in FIG. 7, with the sleeve member removed;

FIG. 9 is a perspective side view of the anvil assembly shown with thehead assembly in a first or operable position;

FIG. 10 is a cross-sectional side view of the anvil assembly shown inFIG. 9, in the first or operable position pre-firing;

FIG. 11 is a cross-sectional side view of the anvil assembly shown inFIGS. 9 and 10, in the operable position subsequent to firing;

FIG. 12 is a cross-sectional perspective view of the anvil assemblyshown in FIGS. 9-11, with the head assembly in the second or tiltedposition;

FIG. 13 is an enlarged cross-sectional side view of a portion of theanvil assembly shown in FIGS. 9-12;

FIG. 14 is a perspective side view of an anvil assembly according to analternative embodiment of the present disclosure, in a first or operableposition;

FIG. 15 is a cross-sectional side view of the anvil assembly shown inFIG. 14;

FIG. 16 is a side view of a slide member of the anvil assembly shown inFIGS. 14 and 15;

FIG. 16A is a cross-sectional bottom view taken along line 16A-16A shownin FIG. 16;

FIG. 16B is a cross-sectional top view taken along line 16B-16B shown inFIG. 16;

FIG. 16C is a cross-sectional end view taken along line 16C-16C shown inFIG. 16;

FIG. 16D is a cross-sectional end view taken along line 16D-16D shown inFIG. 16;

FIG. 17 is a cross-sectional perspective view of the anvil assemblyshown in FIGS. 14 and 15, in a second or tilted position;

FIG. 18 is a cross-sectional side view of the anvil assembly shown inFIG. 17;

FIG. 19 is a cross-sectional side view an anvil assembly according toanother embodiment of the present disclosure, in a first or operableposition; and

FIG. 20 is a cross-sectional side view of the anvil assembly shown inFIG. 19, in a second or tilted position.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed anvil assembly will now bedescribed in detail with reference to the drawings in which likereference numerals designate identical or corresponding elements in eachof the several views. As is common in the art, the term “proximal”refers to that part or component closer to the user or operator, i.e.surgeon or clinician, while the term “distal” refers to that part orcomponent further away from the user.

FIGS. 1-13 illustrate a tiltable anvil assembly 10 which is suitable foruse with a surgical stapling device 100 for performing surgicalprocedures, such as, for example, circular anastomoses of hollow tissueorgans and hemorrhoid surgeries. With initial reference to FIG. 1,surgical stapling device 100 includes a proximal handle assembly 102, anelongated central body portion 104 including a curved elongated outertube 104 a, and a distal head portion 106. Alternately, in some surgicalprocedures, e.g., the treatment of hemorrhoids, it is desirable to havea substantially straight, shortened, central body portion. The length,shape and/or the diameter of body portion 104 and distal head portion106 may be varied to suit a particular surgical procedure. Detaileddescriptions of surgical stapler 100 are disclosed in commonly ownedU.S. Pat. Nos. 7,364,060 and 7,303,106 (“the '060 Patent” and “the '106Patent”), the contents of each of which are incorporated herein byreference in their entirety.

Referring to FIGS. 2-5, anvil assembly 10 includes a head assembly 12, acenter rod assembly 14, and a sleeve member 15. Sleeve member 15 isconfigured to reposition an anastomosis donut and/or other tissue orobstruction (not shown) about center rod assembly 14 following thefiring of surgical stapling device 100 to allow head assembly 12 topivot relative to center rod assembly 14 without pinching theanastomosis donut between head assembly 12 and center rod assembly 14 asdescribed in further detail below. As described above, an anastomosisdonut is the tissue severed from the anastomosis site by an annularknife of a circular stapling device during an anastomosis procedureusing a circular stapling device.

In one embodiment, head assembly 12 includes a post 16, a housing 18, abackup member or plate 20, a cutting ring 22, a cutting ring cover 23,an anvil plate 24, a cam latch member 26, and a retainer member 27. Asshown, post 16 is monolithically formed with and centrally positionedwithin head 18. Alternatively, post 16 and head 18 may be formed asseparate that are joined using, adhesives, welding or any other suitablemethod. As will be described in further detail below, post 16 includes apair of nubs 16 a (FIG. 8) configured to engage anvil center rodassembly 14 to prevent counter-clockwise rotation of head assembly 12relative to anvil center rod assembly 14. Anvil plate 24 is supported inan outer annular recess 28 (FIG. 3) of housing 18 and includes aplurality of staple deforming pockets 30 for receiving and deformingstaples (not shown). At least one tab 24 a extends radially outwardlyfrom anvil plate 24 and is received within a cutout 32 formed in anouter rim of housing 18. Tab 24 a and cutout 32 function to align orproperly position anvil plate 24 within annular recess 28 of housing 18.

With particular reference to FIG. 3, backup plate 20 includes a centralopening 34 which is positioned about post 16 within an inner annularrecess 36 of housing 18 between post 16 and outer annular recess 28.Backup plate 20 includes a raised platform 20 a. Cutting ring 22includes an opening 22 a having a configuration substantially the sameas platform 20 a. In one embodiment, cutting ring 22 is formed frompolyethylene, or other suitable plastic, and is fixedly secured tobackup plate 20 using, for example, an adhesive, to form a backupplate/cutting ring assembly. Backup plate 20 is formed from a hardmaterial, e.g., a metal. Alternately other materials of construction maybe used to construct backup plate 20 and cutting ring 22. Further,backup plate 20 and cutting ring 22, in the alternative, may be formedas a single or unitary structure.

A cutting ring cover 23 may be secured to an outwardly facing orproximal surface 40 of cutting ring 22 using, for example, an adhesive.Cutting ring 22 and backup plate 20 are slidably mounted about post 16.Backup plate 20 includes a pair of inwardly extending fingers 38 whichwill be described in further detail below. Retainer member 27 ispositioned in inner annular recess 36 between backup plate 20 and a backwall 18 a of housing 18 and prevents backup plate 20 and cutting ring 22from moving or being pushed into inner annular recess 36 of housing 18until a predetermined force sufficient to deform tabs 27 a has beenapplied to the backup plate/cutting ring assembly. The predeterminedforce may be close to but is less than the force applied by an annularcutting blade of a surgical stapling device when it engages, forexample, the cutting ring of anvil assembly 10. When the predeterminedforce is reached, e.g., during cutting of tissue, backup plate 20 isurged into inner annular recess 36 and compresses tabs 27 a of retainermember 27.

Anvil center rod assembly 14 includes a center rod 52, a plunger 54, andph spring 56. A first end of center rod 52 has a pair of arms 59 whichdefine a cavity 59 a. Each arm 59 has a transverse throughbore 58 whichis aligned with a central longitudinal axis of center rod 52. Post 16 ofanvil head assembly 12 is dimensioned to be positioned within cavity 59a and includes a transverse throughbore 60. A pivot ember 62 pivotablysecures post 16 to center rod 52 via throughbores 58 and 60 such thatanvil head assembly 12 is pivotably mounted to anvil center rod assembly14.

With particular reference to FIGS. 3 and 4, cam latch member 26 includesa body 26 a having a throughbore 26 b. Throughbore 26 b is dimensionedto receive pivot member 62 such that cam latch member 26 is pivotallymounted within transverse slot 72 (FIG. 3) of post 16 about pivot member62. As shown in FIG. 4, cam latch member 26 includes a first bodyportion 26 c which extends partially from slot 72 (FIG. 3) of post 16and is positioned to be engaged by finger 66 of plunger 54. Cam latchmember 26 also includes an edge 26 f which is urged into engagement withan inner periphery of backup plate 20 (FIG. 10) by finger 66 of plunger54 when anvil head 12 is in the non-tilted or operative position. Camlatch member 26 further includes a connector portion 26 g which definesa throughbore 2611 dimensioned to receive a pivot member 94 (FIG. 6) ofsleeve member 15 such that cam latch member 26 is pivotally secured tosleeve member 15. Alternatively, cam latch member 26 and sleeve member15 may be connected by a pivot member (not shown) extending fromconnector portion 26 g of cam latch member 26 into engagement with anopening (not shown) formed in sleeve member 15.

Referring to FIG. 10, plunger 54 is slidably positioned in a bore 64formed in the first end of center rod 52. Plunger 54 includes anengagement finger 66 which is offset from the pivot axis of anvil headassembly 12 and is biased into engagement with an edge 26 c of cam latchmember 26. As will be described in further detail below, engagement offinger 66 with edge 26 c of cam latch member 26 presses edge 26 fagainst an inner periphery of back plate 20 and post 16 to urge anvilhead assembly 12 to the pivoted or tilted position (FIG. 12) on centerrod 52. In the pre-fired position, fingers 38 formed on backup plate 20are positioned adjacent top surface 52 a and protrusions 52 b of centerrod 52 to prevent anvil head assembly 12 from pivoting about pivotmember 62 (FIG. 7). When anvil assembly 10 is attached to surgicalstapling device 100 (FIG. 1) and the device is fired in the mannerdescribed in the '106 Patent, backup plate 20 and cutting ring 22 arepushed into inner annular recess 36 of housing 18 about post 16, in thedirection indicated by arrow “A” in FIG. 11, by a knife blade (notshown). When this occurs, fingers 38 move into annular recess 36 awayfrom top surface 52 a and protrusions 52 b of center rod 52 to permitplunger 54 (FIG. 11) to pivot anvil head assembly 12 about pivot member62. Retainer member 27 prevents inadvertent or premature movement ofbackup plate 20 into inner annular recess 36 to prevent premature orinadvertent tilting of anvil head assembly 12.

Referring now to FIGS. 3 and 10, a second end of center rod 52 includesa bore 80 defined by a plurality of flexible arms 82. Flexible arms 82each include an opening 82 a dimensioned to receive a projection firmedon or connected to a removable trocar (not shown) or the like. Thedistal ends of each of flexible arms 82 include an internal shoulder 84(FIG. 10) dimensioned to releasably engage an anvil retainer (not shown)of a surgical stapling device 100 (FIG. 1) to secure anvil assembly 10to surgical stapling device 100. A plurality of splines 86 are formedabout center rod 52. Splines 86 function to align anvil assembly 10 withthe staple holding portion of surgical stapling device 100.

With particular reference now to FIGS. 6-6D, sleeve member 15 includes asleeve body 90 and a flange 92 extending distally from sleeve body 90.Sleeve body 90 is substantially tubular and is configured to be receivedabout a distal end of center rod 52 (FIG. 7) of center rod assembly 14and to extend across the tissue gap defined between anvil plate 24 and adistal end of shell assembly 108 (FIG. 1). Sleeve body 90 is sized anddimensioned to slide proximally, as indicated by arrows “C” in FIG. 13,from a distal-most first position on center rod 52 when anvil assembly10 is in the first or operable position (FIG. 9) to a proximal positionon center rod 52 (FIG. 13) as head assembly 12 pivots relative to anvilcenter rod assembly 14.

Sleeve body 90 optionally includes annular lips 90 a, 90 b formed onproximal and distal ends, respectively. Annular lips 90 a, 90 b areconfigured to maintain the anastomosis donut and/or other tissue orobstruction (not shown) about sleeve body 90 as sleeve body 90 is movedproximally about center rod 52 during pivoting of head assembly 12 fromthe operable position to the tilted position. As described above, duringan anastomosis procedure, the first and/or second sections of the tissuebeing joined (not shown) may be secured to anvil assembly 10 using apurse string suture(s) (not shown). The purse string suture(s)facilitate positioning and securing of the anastomosis donut aboutsleeve body 90. Sleeve body 90 defines notch 91 configured toaccommodate post 16 and cam latch member 26 (FIG. 3) of head assembly 12when sleeve body 90 is in the first, distal-most position (FIG. 9).Sleeve body 90 further defines a longitudinal slot 93 configured toaccommodate finger 66 of plunger 54 of anvil center rod assembly 14 whensleeve body 90 is in the first, distal-most position (FIG. 9).

Flange 92 extends distally from sleeve body 90 and engages cam latchmember 26 of head assembly 12. A first end 92 a of flange 92 forms aliving hinge with sleeve body 90 to permit flexing of flange 92 relativeto sleeve body 90. A second end 92 b of flange 92 is pivotally securedto connector portion 26 g (FIG. 4) of cam latch member 26 of headassembly 12. As shown, flange 92 includes a pivot member 94 which ispivotally received within throughbore 26 h formed in connector portion26 g of cam latch member 26. As noted above, in an alternativeembodiment, cam latch member 26 may instead include a pivot member (notshown) configured for reception within an opening (not shown) defined byflange 92 of sleeve body 90. Flange 92 is slidably supported adjacentcenter rod 52 between sleeve member 15 and cam latch member 26 as camlatch member 26 is pivoted by finger 66 of plunger 54 during pivoting ofhead assembly 12 from the first position (FIG. 9) to the second position(FIG. 12). As cam latch member 26 pivots from the first position to thesecond position, the connection between connector portion 26 g andflange 92 results in sleeve body 90 moving proximally, as indicated byarrows “C” in FIG. 13, from a distal-most position about center rod 52to a proximal position. As described above, proximal movement of sleevebody 90 about center rod 52 relocates an anastomosis donut and/or othertissue or obstruction (not shown) formed during the anastomosisprocedure to prevent pinching of the anastomosis donut, tissue and/orobstruction by head assembly 12 as head assembly 12 is pivoted to atilted position (FIG. 12).

Referring to FIGS. 7 and 10, when anvil assembly 10 is in the prefirednon-tilted position, backup plate 20 is spaced from back wall 18 a ofhousing 18 by retainer 27 and fingers 38 of backup plate 20 arepositioned adjacent top surface 52 a and protrusion 52 b of center rod52 to prevent tilting of anvil head assembly 12 about pivot member 62.In the non-tilted position, sleeve body 90 covers the tilting mechanism,i.e., post 16 and cam latch member 26 of head assembly 12 and arms 59 ofcenter rod 52 and pivot member 62, of tiltable anvil assembly 10.

Still referring to FIG. 10, finger 66 of plunger 54 is urged by spring56 into engagement with body portion 26 c of cam latch member 26 andpost 16 to urge cam latch member 26 and head assembly 12 in a clockwisedirection about pivot member 62 such that edge 26 f of cam latch member26 engages an inner periphery 20 b of backup member 20 and anvil headassembly 12 move towards the tilted position (FIG. 12). The tilting oftiltable anvil assembly 10 facilitates insertion and/or removal of theanvil assembly to/from a hollow organ.

Referring to FIGS. 10 and 11, when anvil assembly 10 is attached to astapling device 100 (FIG. 1) and the device is fired, a knife blade (notshown) of the stapling device engages cutting ring 22 to move cuttingring 22 (FIG. 3) and backup plate 20 in the direction indicated by arrow“A” in FIG. 11 into annular recess 36 of housing 18 of anvil headassembly 12. When this occurs, deformable tabs 27 a (FIG. 3) of retainer27 are deformed against back wall 18 a of housing 18 and fingers 38 ofbackup member 20 move away from top surface 52 a and protrusions 52 b ofcenter rod 52. Thereafter, engagement of plunger 54 with cam latchmember 26 and subsequently with post 16 rotates cam latch member 36 andanvil head assembly 12 towards the tilted position (FIG. 12). It isnoted that anvil head assembly 12 will not immediately tilt upon firingof stapling device 100 (FIG. 1) because, upon firing, anvil headassembly 12 is in an approximated position, i.e., the anvil headassembly 12 is in close alignment with shell assembly 108 (FIG. 1) ofsurgical stapling device 100 (FIG. 1). As such, the anvil head assembly12 will begin to tilt as anvil head assembly 12 and shell assembly 108of the stapling device 100 are unapproximated.

Referring to FIGS. 12 and 13, as anvil head assembly 12 pivots wards itstilted position, linger 66 of plunger 54 maintains surface 26 e of camlatch member 26 in contact with backup plate 20 to prevent backup plate20 from sticking to the knife blade as the knife blade is retracted. Itis noted that curved surface 26 e of cam latch member is configured toeliminate any gap and ensure contact between surface 26 e of cam latchmember 26 and backup plate 20 to hold backup plate 20 in place duringand after the knife blade is retracted such that the cutting ring andbackup plate assembly stay in their correct position during tilting ofanvil assembly 12.

As anvil head assembly 12 pivots towards the tilted position, pivotalengagement of flange 92 of sleeve member 15 with cam latch member 26causes sleeve body 90 to slide proximally about center rod 52 of anvilcenter rod assembly 14. More particularly, the pivoting of cam latchmember 26 applies a proximal force to sleeve body 90 through flange 92to effect linear movement of sleeve body 90 about center rod 52. Morespecifically, the pivotal engagement between flange 92 and cam latchmember 26 and the living hinge formed between flange 92 and sleeve body90 allow flange 92 to flex to translate the pivoting motion of cam latchmember 26 into a proximal linear motion of sleeve body 90. In thismanner, the anastomosis donut and/or other tissue or obstruction (notshown) received about sleeve body 90 is moved proximally away from headassembly 12, to prevent pinching of the anastomosis donut and/or othertissue or obstruction between head assembly 12 and anvil center rodassembly 14. As described above, annular lips 90 a, 90 b formed onproximal and distal ends, respectively, of sleeve body 90 engage theanastomosis donut and/or other tissue or obstruction to facilitatemovement of the donut/tissue/obstruction away from the tiltingmechanism.

Although shown and described as being operably connected to cam latchmember 26, it is envisioned that sleeve body 90 of sleeve member 15 mayinstead be operably connected to post 16 of head assembly 12 of anvilassembly 10. Furthermore, although shown as relates to anvil assembly10, it is envisioned that the aspects of the present disclosure may bemodified for use with any anvil assembly having an anvil head capable ofbeing pivoted from a first, operable position, to a second, tiltedposition.

With reference now to FIGS. 14-18, an alternative embodiment of atiltable anvil assembly according to the present disclosure is showngenerally as anvil assembly 110. Anvil assembly 110 is substantiallysimilar to anvil assembly 10 described hereinabove and will only bedescribed as relates to the differences therebetween. Anvil assembly 110includes a head assembly 112, an anvil center rod assembly 114, and asleeve member 115.

Head assembly 112 includes a housing 118 and a post 116. Post 116includes a tab 116 a and an engagement surface 116 b. Tab 116 a of post116 is configured to be loosely received within an opening 191 formed ina sleeve body 190 of sleeve member 115 when anvil assembly 110 is in afirst or operable position (the non-tilted position; see FIGS. 14 and15). Engagement surface 116 b of post 116 is configured to engage adistal end 190 b of sleeve body 190 as head assembly 112 pivots relativeto anvil center rod assembly 114. It is envisioned that post 116 mayfurther include a cam surface for engagement by finger 166 of plunger154 (FIG. 15).

Sleeve member 115 includes sleeve body 190. Sleeve body 190 includes asubstantially tubular member configured to be slidably received about adistal portion of anvil center rod assembly 114 in a sliding manner.Although not shown, sleeve member 115 may include a lip formed about oneor both of proximal and distal ends 190 a, 190 b to facilitate retentionof an anastomosis donut (not shown) about sleeve body 190. As notedabove, sleeve body 190 defines an opening 191 adjacent a distal endconfigured to selectively receive tab 116 a of post 116 of head assembly112. As also noted above, a distal end 190 b of sleeve body 190 isconfigured to be engaged by engagement portion 116 b of post 116 of headassembly 112 during pivoting of head assembly 112 from the first oroperable position (FIGS. 14 and 15) to a second or tilted position(FIGS. 17 and 18). It is envisioned that engagement portion 116 b ofpost 116 may be shaped as a cam surface.

As described above with respect to anvil assembly 10, subsequent tofiring of stapling device 100, head assembly 112 of anvil assembly 110is configured to pivot relative to anvil center rod assembly 114. Ashead assembly 112 pivots to the second tilted position, tab 116 a formedon post 116 of head assembly 112 is withdrawn from within opening 191formed in sleeve body 190 of sleeve assembly 115. As tab 116 a iswithdrawn from opening 191, engagement surface 116 b of post 116 engagesdistal end 190 b of sleeve body 190. Engagement of sleeve body 190 byengagement surface 116 b of post 116 moves sleeve body 190 in a proximaldirection. In this manner, an anastomosis donut (not shown) receivedabout sleeve body 190 is moved proximally away from head assembly 112,to prevent pinching of the anastomosis donut and/or other tissue orobstruction between head assembly 112 and anvil center rod assembly 114as head assembly 112 is pivoted to the tilted position.

With reference now to FIGS. 19 and 20, a tiltable anvil assemblyaccording to another embodiment of the present disclosure is showngenerally as anvil assembly 210. Anvil assembly 210 is substantiallysimilar to anvil assemblies 10 and 110 described hereinabove, andtherefore will only be described as relates to the differencestherebetween. Anvil assembly 210 includes a head assembly 212 and ananvil center rod assembly 214. As will be described in further detailbelow, anvil assembly 210 may be modified for use with either of theabove disclosed sleeve members 15 (FIG. 6), 115 (FIG. 16).

Head assembly 212 includes a housing 218, a post 216, and a cam latchmember 226. Post 216 and cam latch member 226 may be integrally formed.Anvil center rod assembly 214 includes a center rod 252, a plunger 254,and plunger spring 256. Head assembly 212 is pivotally secured to centerrod 252 by a pivot pin 262 which is received within a transversethroughbore (not shown) defined by post 216 and a pair of arms 259 ofcenter rod 252. Cam latch member 226 defines a bore 258 which alsoreceives pivot pin 262 to pivotally secure cam latch member 226 aboutpivot pin 262.

Transverse throughbore 258 is offset, i.e., laterally spaced, relativeto a central longitudinal axis “x” of center rod 252, as indicated byreference character “y” in FIG. 19. By offsetting pivot pin 262 relativeto central longitudinal axis “x”, the distance between pivot pin 262 anda finger 266 of plunger 254, as indicated by reference character “z” inFIG. 19, is increased Increasing the distance between pivot pin 262 andplunger 254 increases the tilting torque applied to head assembly 212 byplunger 254 without increasing the outer diameter of center rod 252.Increasing the tilting torque applied to head assembly 212 by plunger254 increases the head tilting performance of anvil assembly 210. Inparticular, the offset arrangement of pivot pin 262 relative tolongitudinal axis “x” permits the pivoting of head assembly 212 relativeto anvil center rod assembly 214 when tissue or other obstructiondisposed between head assembly 212 and anvil center rod assembly 214might otherwise prevent head assembly 212 from pivoting relative tocenter rod assembly 214.

Anvil assembly 210 operates in a similar manner to anvil assemblies 10and 110, described hereinabove. In particular, following actuation ofsurgical stapling device 100 (FIG. 1), engagement of a finger 266 ofplunger 254 with cam latch member 226 rotates cam latch member 226within housing 218 such that cam latch member 226 engages backup plate220 to hold backup plate 220 in place as a knife blade (not shown) ofsurgical stapling device 10 (FIG. 1) is retracted. Finger 266 of plunger254 also engages post 216 of head assembly 212 to cause pivoting of headassembly 212 relative to anvil center rod assembly 214 as head assembly212 is moved away from shell assembly 108 (FIG. 1) of surgical staplingdevice 10 (FIG. 1).

In an alternative embodiment, an outer diameter of center rod 252 may beincreased to accommodate a plunger (not shown) having a finger (notshown) that is spaced further from longitudinal axis “x” to increase thedistance between pivot pin 262 and the finger of the plunger, therebyincreasing the tilting torque applied by the finger to head assembly212.

Any of the above disclosed embodiments may be modified for use with thesurgical stapling instruments disclosed in commonly owned U.S. patentapplication Ser. No. 13/444,998 filed Apr. 12, 2012 and U.S. patentapplication Ser. No. 13/915,953 filed Jun. 12, 2013, the contents ofwhich are incorporated herein by reference in their entirety.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, the presently disclosedsleeve assemblies may be modified for use on an anvil assembly having ahead assembly capable of one hundred and twenty degrees (120°) of tilt,i.e., capable of being pivoted in a counter-clockwise direction prior tofiring to facilitate positioning of the anvil assembly within a lumen.Those skilled in the art will envision other modifications within thescope and spirit of the claims appended hereto.

What is claimed is:
 1. An anvil assembly comprising: an anvil center rodassembly; a head assembly pivotally secured to the anvil center rodassembly from an operative position to a tilted position; and a sleeveincluding a tubular sleeve body positioned about the anvil center rodassembly and a flange pivotally secured to the head assembly, whereinmovement of the head assembly from the operative position towards thetilted position effects proximal movement of the sleeve about the anvilcenter rod assembly.
 2. The anvil assembly of claim 1, wherein the headassembly includes a housing, a post, a backup plate, and a cam latchmember.
 3. The anvil assembly of claim 2, wherein the backup plate ispositioned to prevent pivotal movement of the head assembly from thenon-tilted position to the tilted position prior to firing of a surgicalstapling device.
 4. The anvil assembly of claim 3, wherein the backupplate is movable to a second position to permit pivotal movement of thehead assembly in relation to the anvil center rod assembly from thenon-tilted position to the tilted position.
 5. The anvil assembly ofclaim 1, wherein a living hinge is formed between the flange and thesleeve body.
 6. The anvil assembly of claim 1, wherein the head assemblyincludes a pivotal cam latch member and the flange is pivotallyconnected to the cam latch member.
 7. The anvil assembly of claim 1,wherein the anvil head assembly includes a post which is pivotallysecured to the anvil center rod assembly, the sleeve being operablyengaged to the post.
 8. The anvil assembly of claim 7, wherein thesleeve is operably positioned to be engaged by the head assembly as thehead assembly is pivoted from the operative position to the tiltedposition.
 9. The anvil assembly of claim 1, wherein the head assembly ispivotally secured to the anvil center rod assembly about a pivot pin,wherein the pivot pin is offset from the longitudinal axis of the anvilcenter rod.
 10. The anvil assembly of claim 2, wherein the flange ispivotally secured to the cam latch member about a pivot pin, wherein thepivot pin is offset from the longitudinal axis of the anvil center rod.11. The anvil assembly of claim 1, wherein the flange extends from thesleeve body.
 12. The anvil assembly of claim 1, wherein the flangeextends distally from the sleeve body.
 13. The anvil assembly of claim1, wherein the sleeve body is positioned entirely about the anvil centerrod assembly.
 14. An anvil assembly comprising: an anvil center rodassembly; a head assembly pivotally secured to the anvil center rodassembly from an operative position to a tilted position; and a sleeveincluding a sleeve body positioned entirely about the anvil center rodassembly and a flange pivotally secured to the head assembly, whereinmovement of the head assembly from the operative position towards thetilted position effects proximal movement of the sleeve about the anvilcenter rod assembly.
 15. The anvil assembly of claim 14, wherein thehead assembly includes a housing, a post, a backup plate, and a camlatch member.
 16. The anvil assembly of claim 15, wherein the backupplate is positioned to prevent pivotal movement of the head assemblyfrom the non-tilted position to the tilted position prior to firing of asurgical stapling device.
 17. The anvil assembly of claim 16, whereinthe backup plate is movable to a second position to permit pivotalmovement of the head assembly in relation to the anvil center rodassembly from the non-tilted position to the tilted position.
 18. Theanvil assembly of claim 14, wherein a living hinge is formed between theflange and the sleeve body.
 19. The anvil assembly of claim 14, whereinthe head assembly is pivotally secured to the anvil center rod assemblyabout a pivot pin, wherein the pivot pin is offset from the longitudinalaxis of the anvil center rod.
 20. The anvil assembly of claim 15,wherein the flange is pivotally secured to the cam latch member about apivot pin, wherein the pivot pin is offset from the longitudinal axis ofthe anvil center rod.